Signal transmission apparatus and a method of signal transmission

An apparatus and method of transmitting a plurality of polarized signals having different wavelengths through a length of signal transmission cable which changes the polarization of the signals in correspondence with their amplitudes and wavelengths. A dynamic filter capable of differential adjustment of the amplitudes of the signals and a polarizing element are provided in series with the length of signal transmission cable and the amplitudes of the different wavelength signals are so adjusted that the polarization states of the signals move towards alignment with the low-loss axis of the polarizing element. An advantage provided by the apparatus and method is that the high-amplitude signals are aligned with the low-loss axis of the polarizing element while low-amplitude noise is aligned with the high-loss axis of the polarizing element, resulting in an improvement in signal-to-noise ratio.